Mixing additives with lubricating oils to improve the detergent-dispersant properties of such oils is known. The use of such additives has been described, for example, in European Pat. Nos. 3694, 6796, 7260 and 7257. Those patents describe processes for preparing alkylphenoxidealkylbenzenesulfonates of alkaline-earth metals which are said to have a Total Basic Number (TBN), as determined by ASTM Standard D-2896, in excess of 200 or 250. Experience has shown, however, that the processes disclosed therein do not enable the preparation of an additive having a TBN of 300 or more.